Fix: set cosine distance metadata on all collection creation sites

ChromaDB defaults HNSW index to L2 (Euclidean) distance, but
MemPalace scoring uses 1-distance which requires cosine (range 0-2).
Add metadata={"hnsw:space": "cosine"} to the 4 production and 3 test
call sites that were missing it.

Closes #218

tests/conftest.py

@@ -101,7 +101,9 @@ def config(tmp_dir, palace_path):
 def collection(palace_path):
     """A ChromaDB collection pre-seeded in the temp palace."""
     client = chromadb.PersistentClient(path=palace_path)
-    col = client.get_or_create_collection("mempalace_drawers")
+    col = client.get_or_create_collection(
+        "mempalace_drawers", metadata={"hnsw:space": "cosine"}
+    )
     yield col
     client.delete_collection("mempalace_drawers")
     del client
@@ -185,7 +187,9 @@ def seeded_kg(kg):
     kg.add_triple("Alice", "parent_of", "Max", valid_from="2015-04-01")
     kg.add_triple("Max", "does", "swimming", valid_from="2025-01-01")
     kg.add_triple("Max", "does", "chess", valid_from="2024-06-01")
-    kg.add_triple("Alice", "works_at", "Acme Corp", valid_from="2020-01-01", valid_to="2024-12-31")
+    kg.add_triple(
+        "Alice", "works_at", "Acme Corp", valid_from="2020-01-01", valid_to="2024-12-31"
+    )
     kg.add_triple("Alice", "works_at", "NewCo", valid_from="2025-01-01")
 
     return kg

tests/test_backends.py

@@ -82,6 +82,20 @@ def test_chroma_backend_create_true_creates_directory_and_collection(tmp_path):
     client.get_collection("mempalace_drawers")
 
 
+def test_chroma_backend_creates_collection_with_cosine_distance(tmp_path):
+    palace_path = tmp_path / "palace"
+
+    ChromaBackend().get_collection(
+        str(palace_path),
+        collection_name="mempalace_drawers",
+        create=True,
+    )
+
+    client = chromadb.PersistentClient(path=str(palace_path))
+    col = client.get_collection("mempalace_drawers")
+    assert col.metadata.get("hnsw:space") == "cosine"
+
+
 def test_fix_blob_seq_ids_converts_blobs_to_integers(tmp_path):
     """Simulate a ChromaDB 0.6.x database with BLOB seq_ids and verify repair."""
     db_path = tmp_path / "chroma.sqlite3"

tests/test_mcp_server.py

@@ -30,7 +30,12 @@ def _get_collection(palace_path, create=False):
 
     client = chromadb.PersistentClient(path=palace_path)
     if create:
-        return client, client.get_or_create_collection("mempalace_drawers")
+        return (
+            client,
+            client.get_or_create_collection(
+                "mempalace_drawers", metadata={"hnsw:space": "cosine"}
+            ),
+        )
     return client, client.get_collection("mempalace_drawers")
 
 
@@ -92,7 +97,9 @@ class TestHandleRequest:
     def test_notifications_initialized_returns_none(self):
         from mempalace.mcp_server import handle_request
 
-        resp = handle_request({"method": "notifications/initialized", "id": None, "params": {}})
+        resp = handle_request(
+            {"method": "notifications/initialized", "id": None, "params": {}}
+        )
         assert resp is None
 
     def test_ping_returns_empty_result(self):
@@ -113,7 +120,9 @@ class TestHandleRequest:
         assert "mempalace_add_drawer" in names
         assert "mempalace_kg_add" in names
 
-    def test_null_arguments_does_not_hang(self, monkeypatch, config, palace_path, seeded_kg):
+    def test_null_arguments_does_not_hang(
+        self, monkeypatch, config, palace_path, seeded_kg
+    ):
         """Sending arguments: null should return a result, not hang (#394)."""
         _patch_mcp_server(monkeypatch, config, seeded_kg)
         from mempalace.mcp_server import handle_request
@@ -218,7 +227,9 @@ class TestReadTools:
         assert result["total_drawers"] == 0
         assert result["wings"] == {}
 
-    def test_status_with_data(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_status_with_data(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_status
 
@@ -235,7 +246,9 @@ class TestReadTools:
         assert result["wings"]["project"] == 3
         assert result["wings"]["notes"] == 1
 
-    def test_list_rooms_all(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_list_rooms_all(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_list_rooms
 
@@ -244,7 +257,9 @@ class TestReadTools:
         assert "frontend" in result["rooms"]
         assert "planning" in result["rooms"]
 
-    def test_list_rooms_filtered(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_list_rooms_filtered(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_list_rooms
 
@@ -252,7 +267,9 @@ class TestReadTools:
         assert "backend" in result["rooms"]
         assert "planning" not in result["rooms"]
 
-    def test_get_taxonomy(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_get_taxonomy(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_get_taxonomy
 
@@ -273,7 +290,9 @@ class TestReadTools:
 
 
 class TestSearchTool:
-    def test_search_basic(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_search_basic(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_search
 
@@ -284,14 +303,18 @@ class TestSearchTool:
         top = result["results"][0]
         assert "JWT" in top["text"] or "authentication" in top["text"].lower()
 
-    def test_search_with_wing_filter(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_search_with_wing_filter(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_search
 
         result = tool_search(query="planning", wing="notes")
         assert all(r["wing"] == "notes" for r in result["results"])
 
-    def test_search_with_room_filter(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_search_with_room_filter(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_search
 
@@ -310,7 +333,9 @@ class TestSearchTool:
         assert "results" in result
 
         # Old name takes precedence when both provided
-        result_strict = tool_search(query="JWT", max_distance=999.0, min_similarity=0.01)
+        result_strict = tool_search(
+            query="JWT", max_distance=999.0, min_similarity=0.01
+        )
         result_loose = tool_search(query="JWT", max_distance=0.01, min_similarity=999.0)
         assert len(result_strict["results"]) <= len(result_loose["results"])
 
@@ -318,7 +343,7 @@ class TestSearchTool:
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace import mcp_server
 
-        monkeypatch.setattr(mcp_server, "_get_collection", lambda *args, **kwargs: pytest.fail())
+        monkeypatch.setattr(mcp_server, "_get_collection", lambda: pytest.fail())
 
         result = mcp_server.tool_list_rooms(wing="../etc/passwd")
         assert "error" in result
@@ -327,7 +352,7 @@ class TestSearchTool:
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace import mcp_server
 
-        monkeypatch.setattr(mcp_server, "search_memories", lambda *args, **kwargs: pytest.fail())
+        monkeypatch.setattr(mcp_server, "search_memories", lambda: pytest.fail())
 
         result = mcp_server.tool_search(query="JWT", room="../backend")
         assert "error" in result
@@ -336,7 +361,7 @@ class TestSearchTool:
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace import mcp_server
 
-        monkeypatch.setattr(mcp_server, "_get_collection", lambda *args, **kwargs: pytest.fail())
+        monkeypatch.setattr(mcp_server, "_get_collection", lambda: pytest.fail())
 
         result = mcp_server.tool_list_drawers(wing="../notes")
         assert "error" in result
@@ -345,7 +370,7 @@ class TestSearchTool:
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace import mcp_server
 
-        monkeypatch.setattr(mcp_server, "_get_collection", lambda *args, **kwargs: pytest.fail())
+        monkeypatch.setattr(mcp_server, "_get_collection", lambda: pytest.fail())
 
         result = mcp_server.tool_find_tunnels(wing_a="../project")
         assert "error" in result
@@ -402,7 +427,9 @@ class TestWriteTools:
         assert result2["success"] is True
         assert result2["reason"] == "already_exists"
 
-    def test_add_drawer_shared_header_no_collision(self, monkeypatch, config, palace_path, kg):
+    def test_add_drawer_shared_header_no_collision(
+        self, monkeypatch, config, palace_path, kg
+    ):
         """Documents sharing a >100-char header must get distinct IDs (full-content hash)."""
         _patch_mcp_server(monkeypatch, config, kg)
         _client, _col = _get_collection(palace_path, create=True)
@@ -414,7 +441,10 @@ class TestWriteTools:
             header
             + "Decision: Use PostgreSQL for primary storage. Rationale: ACID compliance required."
         )
-        doc2 = header + "Decision: Use Redis for session caching. Rationale: sub-ms latency needed."
+        doc2 = (
+            header
+            + "Decision: Use Redis for session caching. Rationale: sub-ms latency needed."
+        )
 
         result1 = tool_add_drawer(wing="work", room="decisions", content=doc1)
         result2 = tool_add_drawer(wing="work", room="decisions", content=doc2)
@@ -425,7 +455,9 @@ class TestWriteTools:
             result1["drawer_id"] != result2["drawer_id"]
         ), "Documents with shared header but different content must have distinct drawer IDs"
 
-    def test_delete_drawer(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_delete_drawer(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_delete_drawer
 
@@ -433,14 +465,18 @@ class TestWriteTools:
         assert result["success"] is True
         assert seeded_collection.count() == 3
 
-    def test_delete_drawer_not_found(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_delete_drawer_not_found(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_delete_drawer
 
         result = tool_delete_drawer("nonexistent_drawer")
         assert result["success"] is False
 
-    def test_check_duplicate(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_check_duplicate(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_check_duplicate
 
@@ -469,14 +505,18 @@ class TestWriteTools:
         assert result["room"] == "backend"
         assert "JWT tokens" in result["content"]
 
-    def test_get_drawer_not_found(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_get_drawer_not_found(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_get_drawer
 
         result = tool_get_drawer("nonexistent_drawer")
         assert "error" in result
 
-    def test_list_drawers(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_list_drawers(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_list_drawers
 
@@ -504,7 +544,9 @@ class TestWriteTools:
         assert result["count"] == 2
         assert all(d["room"] == "backend" for d in result["drawers"])
 
-    def test_list_drawers_pagination(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_list_drawers_pagination(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_list_drawers
 
@@ -522,7 +564,9 @@ class TestWriteTools:
         result = tool_list_drawers(offset=-5)
         assert result["offset"] == 0
 
-    def test_update_drawer_content(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_update_drawer_content(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_update_drawer, tool_get_drawer
 
@@ -540,19 +584,25 @@ class TestWriteTools:
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_update_drawer
 
-        result = tool_update_drawer("drawer_proj_backend_aaa", wing="new_wing", room="new_room")
+        result = tool_update_drawer(
+            "drawer_proj_backend_aaa", wing="new_wing", room="new_room"
+        )
         assert result["success"] is True
         assert result["wing"] == "new_wing"
         assert result["room"] == "new_room"
 
-    def test_update_drawer_not_found(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_update_drawer_not_found(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_update_drawer
 
         result = tool_update_drawer("nonexistent_drawer", content="hello")
         assert result["success"] is False
 
-    def test_update_drawer_noop(self, monkeypatch, config, palace_path, seeded_collection, kg):
+    def test_update_drawer_noop(
+        self, monkeypatch, config, palace_path, seeded_collection, kg
+    ):
         _patch_mcp_server(monkeypatch, config, kg)
         from mempalace.mcp_server import tool_update_drawer
 

tests/test_miner.py

@@ -27,7 +27,8 @@ def test_project_mining():
         os.makedirs(project_root / "backend")
 
         write_file(
-            project_root / "backend" / "app.py", "def main():\n    print('hello world')\n" * 20
+            project_root / "backend" / "app.py",
+            "def main():\n    print('hello world')\n" * 20,
         )
         with open(project_root / "mempalace.yaml", "w") as f:
             yaml.dump(
@@ -59,7 +60,9 @@ def test_scan_project_respects_gitignore():
         write_file(project_root / ".gitignore", "ignored.py\ngenerated/\n")
         write_file(project_root / "src" / "app.py", "print('hello')\n" * 20)
         write_file(project_root / "ignored.py", "print('ignore me')\n" * 20)
-        write_file(project_root / "generated" / "artifact.py", "print('artifact')\n" * 20)
+        write_file(
+            project_root / "generated" / "artifact.py", "print('artifact')\n" * 20
+        )
 
         assert scanned_files(project_root) == ["src/app.py"]
     finally:
@@ -74,7 +77,9 @@ def test_scan_project_respects_nested_gitignore():
         write_file(project_root / ".gitignore", "*.log\n")
         write_file(project_root / "subrepo" / ".gitignore", "tasks/\n")
         write_file(project_root / "subrepo" / "src" / "main.py", "print('main')\n" * 20)
-        write_file(project_root / "subrepo" / "tasks" / "task.py", "print('task')\n" * 20)
+        write_file(
+            project_root / "subrepo" / "tasks" / "task.py", "print('task')\n" * 20
+        )
         write_file(project_root / "subrepo" / "debug.log", "debug\n" * 20)
 
         assert scanned_files(project_root) == ["subrepo/src/main.py"]
@@ -133,7 +138,9 @@ def test_scan_project_can_disable_gitignore():
         write_file(project_root / ".gitignore", "data/\n")
         write_file(project_root / "data" / "stuff.csv", "a,b,c\n" * 20)
 
-        assert scanned_files(project_root, respect_gitignore=False) == ["data/stuff.csv"]
+        assert scanned_files(project_root, respect_gitignore=False) == [
+            "data/stuff.csv"
+        ]
     finally:
         shutil.rmtree(tmpdir)
 
@@ -146,7 +153,9 @@ def test_scan_project_can_include_ignored_directory():
         write_file(project_root / ".gitignore", "docs/\n")
         write_file(project_root / "docs" / "guide.md", "# Guide\n" * 20)
 
-        assert scanned_files(project_root, include_ignored=["docs"]) == ["docs/guide.md"]
+        assert scanned_files(project_root, include_ignored=["docs"]) == [
+            "docs/guide.md"
+        ]
     finally:
         shutil.rmtree(tmpdir)
 
@@ -215,7 +224,9 @@ def test_file_already_mined_check_mtime():
         palace_path = os.path.join(tmpdir, "palace")
         os.makedirs(palace_path)
         client = chromadb.PersistentClient(path=palace_path)
-        col = client.get_or_create_collection("mempalace_drawers")
+        col = client.get_or_create_collection(
+            "mempalace_drawers", metadata={"hnsw:space": "cosine"}
+        )
 
         test_file = os.path.join(tmpdir, "test.txt")
         with open(test_file, "w") as f:
@@ -269,7 +280,9 @@ def test_mine_dry_run_with_tiny_file_no_crash():
         project_root = Path(tmpdir).resolve()
 
         # One normal file and one that falls below MIN_CHUNK_SIZE
-        write_file(project_root / "good.py", "def main():\n    print('hello world')\n" * 20)
+        write_file(
+            project_root / "good.py", "def main():\n    print('hello world')\n" * 20
+        )
         write_file(project_root / "tiny.txt", "x")
 
         with open(project_root / "mempalace.yaml", "w") as f: